The Constant Geometric Speed Schedule for Adiabatic State Preparation

Fuente: arXiv
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Autores principales: Han, Mancheon, Park, Hyowon, Choi, Sangkook
Formato: Preprint
Publicado: 2025
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author Han, Mancheon
Park, Hyowon
Choi, Sangkook
author_facet Han, Mancheon
Park, Hyowon
Choi, Sangkook
contents The efficiency of adiabatic quantum evolution is governed by the evolution time $T$, which typically scales as $\mathcal{O}(Δ^{-2})$ with the minimum energy gap $Δ$. However, the rigorous lower bound is $\mathcal{O}(LΔ^{-1})$, where $L$ is the adiabatic path length. Although $L$ is formally upper-bounded by $\mathcal{O}(Δ^{-1})$, such a bound is often too loose in practice, and $L$ can be bounded independently of $Δ$. This indicates the potential for a quadratic speedup through adiabatic schedule construction. Here, we introduce the constant geometric speed (CGS) schedule, which traverses the adiabatic path at a uniform rate. We show that this approach reduces the scaling of the evolution time by a factor of $Δ^{-1}$, provided $L$ remains bounded independently of $Δ$. We propose a segmented CGS protocol where path segment lengths are computed from eigenstate overlaps on the fly, reducing the prior spectral-knowledge requirement from the full gap function $Δ(s)$ to just a global lower bound on the energy gap. Numerical tests on adiabatic unstructured search, N$_2$, and a [2Fe-2S] cluster demonstrate the optimal $Δ^{-1}$ scaling, confirming a quadratic speedup over the standard linear schedule.
format Preprint
id arxiv_https___arxiv_org_abs_2510_01923
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Constant Geometric Speed Schedule for Adiabatic State Preparation
Han, Mancheon
Park, Hyowon
Choi, Sangkook
Quantum Physics
The efficiency of adiabatic quantum evolution is governed by the evolution time $T$, which typically scales as $\mathcal{O}(Δ^{-2})$ with the minimum energy gap $Δ$. However, the rigorous lower bound is $\mathcal{O}(LΔ^{-1})$, where $L$ is the adiabatic path length. Although $L$ is formally upper-bounded by $\mathcal{O}(Δ^{-1})$, such a bound is often too loose in practice, and $L$ can be bounded independently of $Δ$. This indicates the potential for a quadratic speedup through adiabatic schedule construction. Here, we introduce the constant geometric speed (CGS) schedule, which traverses the adiabatic path at a uniform rate. We show that this approach reduces the scaling of the evolution time by a factor of $Δ^{-1}$, provided $L$ remains bounded independently of $Δ$. We propose a segmented CGS protocol where path segment lengths are computed from eigenstate overlaps on the fly, reducing the prior spectral-knowledge requirement from the full gap function $Δ(s)$ to just a global lower bound on the energy gap. Numerical tests on adiabatic unstructured search, N$_2$, and a [2Fe-2S] cluster demonstrate the optimal $Δ^{-1}$ scaling, confirming a quadratic speedup over the standard linear schedule.
title The Constant Geometric Speed Schedule for Adiabatic State Preparation
topic Quantum Physics
url https://arxiv.org/abs/2510.01923